Confinement by Carbon Nanotubes Drastically Alters the Boiling and Critical Behavior of Water Droplets

TL;DR

This study uses atomistic simulations to show that water droplets inside carbon nanotubes disintegrate at lower temperatures and that CNT size controls internal pressure, which could aid drug delivery.

Contribution

It reveals how confinement in carbon nanotubes reverses typical boiling and critical behaviors of water droplets, highlighting size-dependent pressure control.

Findings

Droplets disintegrate first inside CNTs at low temperatures.

Disintegration temperature is independent of CNT diameter.

Internal pressure can be controlled by CNT size.

Abstract

Vapor pressure grows rapidly above the boiling temperature, and past the critical point liquid droplets disintegrate. Our atomistic simulations show that this sequence of events is reversed inside carbon nanotubes (CNT). Droplets disintegrate first and at low temperature, while pressure remains small. The droplet disintegration temperature is independent of the CNT diameter. In contrast, depending on CNT diameter, a temperature that is much higher than the bulk boiling temperature is required to raise the internal pressure. The control over pressure by CNT size can be useful for therapeutic drug delivery.